This invention relates to the recovery of electrical conductors such as copper and aluminum from cable, particularly scrap cable. More particularly, the invention is directed to an improved process and apparatus whereby insulative cladding as well as organic fillers such as petroleum jelly are essentially quantitatively separated from the conductive metal element of cables to provide an unoxidized product which may be conveniently and economically reprocessed for re-use in electrical and other industries.
The recovery or reclamation of conductive wire from cables including electrical cables and telephone cables is a practice well established in the art, and various techniques have been used in an effort to devlop improved procedures. Substantially all of the prior art processes include a mechanical chopping step to reduce the cable into convenient incremental lengths to facilitate handling and treatment.
A technique which has been used extensively in the past is to subject particulate cable to a combustion step to burn off the organic components. It will be appreciated that this particular procedure poses serious air contamination problems and ecological hazards. In addition, the conductive metal, for example copper, is undesirably oxidized during the process. In other prior art processes an autoclaving step is used to remove the insulative sheaths from cables, particularly sheaths of plastic material such as polyvinylchloride. The "cooking" step in the autoclave is carried out in the presence of an "oil" which may be a petroleum distillate. This process is extremely sensitive and demands careful control of the ratio of plastic to the metal which is subjected to the treatment. It is also highly sensitive to the type of plastic sheathing involved. The autoclaving serves merely to render the sheathing material brittle and it is then necessary to remove the sheathing itself in mechanical processing operations.
In the case of cables containing petrolactum-type fillers, clay or diatomaceous earth has been used as an "absorbant" to remove the filler. The technique is inefficient and far from satisfactory.
The scrap material available for reclamation of conductors derives from various sources, and the cable itself may vary in its physical composition and construction. Each particular conductor-sheathing material poses special problems in any reclamation process, and no single process is completely suitable for treating all cable presently being reclaimed. It is to the recovery of electrical conductors from a particular type of cable, namely telephone cable, that the present invention is primarily directed.